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Head Porting - Worth it?


kev
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Trying to start up a debate here...a technical one. Head porting...is it worth it? Most of us know that porting our stock cylinder heads costs from about $400-$800 with flow testing...maybe even more depending on the shop. So does it give the bang for the buck when it comes to a forced air engine?

 

Based on many members opinion's over the years and general car lingo; the more you increase air flow to the combustion chamber, the higher the output of the engine, quicker spool up times, etc etc. However, I saw a thread on here a few weeks back where someone put up a good argument saying that this increase in power is negligible compared with the cost of the modification.

 

Kinda hard to put facts on the table because most of us who port the head are also adding many other goodies to the engine at the same time. So dyno runs, qtr mile times, pre- and post- just porting are hard to find.

 

I'm finally in the process of building my MPI engine and the head machining is next on my list. Of course I'd love to save the cash and not port but I don't want to neglect it and then wish I didn't down the road.

 

kev

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Well sir I am no Guru to start with but you can see in my engine rebuild video I got the M28 from Dad and did a basic gasket match with the ol sharpie technique lol from intake to exhaust and also smoothed out the 14B that had a bracket weld thru the housing lol. I am very particular at times and I did not want to aka cut into the m28 that much but it did have some casting flaws that I smoothed out and polished. I did this as my mechanic overseeing my work. It took me two days split up at his shop for a few hours a piece to get it done and even if it didn't help I sure am glad I did instead of not doing it while it was out of car....oh and the cost...free.

2nd page resto center at 1.42 in video shows port work. My mechanic said better flow is better flow no obstructions and since his toy stang runs 9sec quarter miles I listen to him. Good luck sir.

Edited by traps
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Trying to start up a debate here...a technical one. Head porting...is it worth it? Most of us know that porting our stock cylinder heads costs from about $400-$800 with flow testing...maybe even more depending on the shop. So does it give the bang for the buck when it comes to a forced air engine?

 

Now where alot of people are led astray, is when they say, "a turbo engine, an engine, my brothers fathers friends camaro" We need to remember that all engines are not equal. Brodix does not make heads for a G54B.

 

So with that out of the way, Im going to say NO. BUT!! That depends on the head. The typical M28 in my opinion and experience NO. When you consider the improvements that could be picked up elsewhere with $800+ (because anything less is a homey hookup or shade tree guessing)

 

Based on many members opinion's over the years and general car lingo; the more you increase air flow to the combustion chamber, the higher the output of the engine

 

That is general air flow theory. The more efficient (VE) you make the pump (engine), the more power it will make. This is true. On a G54B the restriction is in the tiny TD05 turbine everyone uses.

 

However, I saw a thread on here a few weeks back where someone put up a good argument saying that this increase in power is negligible compared with the cost of the modification. Kinda hard to put facts on the table because most of us who port the head are also adding many other goodies to the engine at the same time. So dyno runs, qtr mile times, pre- and post- just porting are hard to find. I'm finally in the process of building my MPI engine and the head machining is next on my list. Of course I'd love to save the cash and not port but I don't want to neglect it and then wish I didn't down the road. kev

 

I have shelled out the money on porting and working hand and hand with recognized circle track and drag engine machinists to figure out how to make the head flow. The hard truth is, the M28 has a poor runner design out of the box with little room for improvement. Magna heads on the other hand are a different story. Much better overall design.

 

The best bang for your buck when it comes to headwork, is valve work. And no Im not say +1 OS valves. Im talking "tulip" style stock sized valves with a proper backcut. I took a worked head in and had just valve work done with flow bench verification. It picked up power everywhere. When I put this head back on the engine with the only change being valve work, I had to add fuel everywhere! So that means the previous tune's scheduled fuel map was not meeting the demands of the increased airflow and now was going lean.

 

untouched M28 heads have made big power on numerous occassions.

 

M28 from Dad and did a basic gasket match with the ol sharpie technique lol from intake to exhaust

 

This is an easy DIY task that is very recommend. Its called port matching.

 

My mechanic said better flow is better flow

 

Correct

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No, not worth 4-8 hundred dollars. The primary limitation will always be the turbo choice, particular the hot side. I put a ported head on my car last summer and lost about 150 rpm spool time and about 250 rpm off the top of the power band. The little 18g ran out of breath sooner. ;) So yes the head flowed better, but did little for the performance of the car.

 

Kev, what turbo were you think of using?

Edited by StarquestRescue
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I say it depends also...... have you done everything else to that baby you can possible do? Custom valves, custom lift of those valves, O ringed head ECT.... if your taking it that far might as well do it. This usually goes hand and hand with a much bigger better flowing more efficient turbo too.

 

Think of it like this.... just adding huge injectors just made it hard to tune / fine tune. Adding biger injectors, better flow, biger turbo pushing more air ECT and now you can take advantage of those bigger injectors.

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All correct. A stock M28 benefits from port matching and a general cleanup of casting flaws, I did that on the flatty and can feel great benefit. That head retained the stock size valves. The flatty also got a hybrid 12a06SL2 and the combination allows it to just keep pulling hard from 4K on up as far as I've been willing to go. Stock Aussie roller cam, same specs as the stock slipper setup.

 

But the M28 head along with the stock jet valve head suffer from a terrible SSR or short side radius. It's more of a cliff than a radius, it would take a lot of work by a competent porter with verification to fix it and it would be far in excess of $800. The magna M7 heads have a much improved SSR and some work with them would result in cost effective gains.

 

You can buy an M28 for less than $300 on ebay and pick up a rebuild kit and 06SL2 wheel for maybe $200 total. Having the stock 05 turbine bored for the SL2 wheel is around $70, reuse the rest of the valve train and you've spent maybe $600 for some real upgraded performance.

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you can do 600whp + on an unported stock size valve head.

 

 

 

Imagine a store. (engine)

 

It has a double door entrance, (head) and a single door exit. (turbine/exhaust)

 

You decide you want to make more profit (HP).

 

So you increase the size of your parking lot(compressor wheel upgrade),

add another double door entrance (headwork),

and have a sale.(turn up the boost)

 

Once all these people arrive and fill the store (boost pressure),

then you set them on fire. (combustion)

 

What do you think will happen since you never changed the exit?

Edited by Funky Phil
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All correct. A stock M28 benefits from port matching and a general cleanup of casting flaws, I did that on the flatty and can feel great benefit. That head retained the stock size valves. The flatty also got a hybrid 12a06SL2 and the combination allows it to just keep pulling hard from 4K on up as far as I've been willing to go. Stock Aussie roller cam, same specs as the stock slipper setup.

 

But the M28 head along with the stock jet valve head suffer from a terrible SSR or short side radius. It's more of a cliff than a radius, it would take a lot of work by a competent porter with verification to fix it and it would be far in excess of $800. The magna M7 heads have a much improved SSR and some work with them would result in cost effective gains.

 

You can buy an M28 for less than $300 on ebay and pick up a rebuild kit and 06SL2 wheel for maybe $200 total. Having the stock 05 turbine bored for the SL2 wheel is around $70, reuse the rest of the valve train and you've spent maybe $600 for some real upgraded performance.

 

BAM

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I did the classic port gasket match on the head that is on my car (M28/stock style). i agree that there is no use shoving money into a head with bad port design to start with. On the other hand I have a Magna M6 that I am working on for my eventual MPI build. I will be putting a lot of time and money into that head simply because it starts off better.
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It is important to remember that these heads are ware items. Like the rotors on my sister minivan or my moms malibu that last about 2 or 3 years. Do you really want to replace a $ 2000 head or a $ 900 head the way they go through rotors?
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Cool...great discussion! This is what I was hoping for.

 

I'm really on the fence. I will be match-porting for sure but am contemplating on not going farther with porting.

 

Here is what I have done so far:

 

JE forged with floaters

race prepped rods

o-ringed block

balanced full rotating components

Tim's Monsta Banshee camshaft with 1.6 ratio rollers. SST valves, schneider HD springs.

brand new M28 head still in the box.

Magna intake with SDS 3E system and 72 lbs/hr injectors, 65MM tb

equal length header with 38MM external wastegate and T4 flange

 

haven't selected the turbo yet...way too many options out there on the market and I'm kinda lost on which one to choose. But I'm going for a quick spooling fun to drive street car. Most likely will be necking that T4 header flange down to a T3 or whatever based on the turbo selection.

 

kev

 

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The best bang for your buck when it comes to headwork, is valve work. And no Im not say +1 OS valves. Im talking "tulip" style stock sized valves with a proper backcut. I took a worked head in and had just valve work done with flow bench verification. It picked up power everywhere. When I put this head back on the engine with the only change being valve work, I had to add fuel everywhere! So that means the previous tune's scheduled fuel map was not meeting the demands of the increased airflow and now was going lean.

 

Interesting. So you have had better results from machining the stock valves than starting out with a set of SST valves?

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^ if you have gown that far what's 400-800 more. Though I do agree you could have used the money else where like custom valves, larger, lighter, longer.

 

O and as for the turbo.... don't neck that down if you want to do that it should have been done in the colector of your header. Use the T4 as is.... is it devided?

Edited by jszucs
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What are sst valves?

 

I like the stock size ss (stainless) valves over the over sized ss There are different styles of the oversize. i only know of one maker for the stock size ss valves. In my opinion over size valves compromise the wight of the seat area when paired with a stock size seat.

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No, the header isn't divided. I haven't been able to find a quick spooling T4 turbo yet, but I'm open to opinions for sure.

 

Obviously my plans have changed over the years. Use to want to build the fastest engine I could. Now I just want something quick and fun to drive.

 

 

kev

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What are sst valves?

 

I like the stock size ss (stainless) valves over the over sized ss There are different styles of the oversize. i only know of one maker for the stock size ss valves. In my opinion over size valves compromise the wight of the seat area when paired with a stock size seat.

 

Sorry, I call stainless steel; SST. I have a set of the 1mm oversize stainless valves. Not sure the brand, but they are the same one Dad sells. I also have a set of 83 and 88 style stock valves new in the box.

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No, the header isn't divided. I haven't been able to find a quick spooling T4 turbo yet, but I'm open to opinions for sure.

 

Obviously my plans have changed over the years. Use to want to build the fastest engine I could. Now I just want something quick and fun to drive.

 

 

kev

 

PTE Billet 5858 w/ T4 .68 AR Housing. Youll see all the boost you want in the 3500rpm range.

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How about something along the lines of precision PT5858 CEA and your going to want to spring for the ball baring option too.

 

Thats funny, you mustve been typing when I clicked reply.

 

He shouldnt need to spring for BB either. Unless he want boost all in sooner than 3500.

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...Once all these people arrive and fill the store (boost pressure),

then you set them on fire. (combustion)

 

What do you think will happen since you never changed the exit?

 

This is a trick question. You will get arrested and convicted for murdering people by setting them on fire!

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This is a trick question. You will get arrested and convicted for murdering people by setting them on fire!

 

That an it really effects the volume... and most motors don't work on solid fuel

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Thats funny, you mustve been typing when I clicked reply.

 

He shouldnt need to spring for BB either. Unless he want boost all in sooner than 3500.

 

That is FREAKING CREEPY.... but I am also advocating sprining for the CEA option too.... He did say FASTEST.

 

And just so you got an idea... better save that porting 400-800 for the 600 for the BB option and god knows how much more for the CEA compressor wheel.

Edited by jszucs
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Oh yeah, CEA for sure. I dont think the 5858 comes without...?

 

He said WAS going for FASTEST.

Now he just wants a quick spooling streetcar.

 

5858 would be far from the fastest. ;)

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Oh yeah, CEA for sure. I dont think the 5858 comes without...?

 

He said WAS going for FASTEST.

Now he just wants a quick spooling streetcar.

 

5858 would be far from the fastest. ;)

 

I have never really been into the precision (for no particular reason) so I don't know if it only comes with that wheel.

 

IDK coudn't really come up with any more impresive maps atleast on a T4 frame. I guess you could come up with some wacked out combo that spolls instant but moved like 2CFM though.... not that there would be a point then.

Edited by jszucs
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